Tuberculosis (TB)

What if I had Bacillus Calmette-Guerin (BCG) vaccination for TB?

Bacillus Calmette-Guérin (BCG) is a vaccine for tuberculosis. It is often given to infants and young children in countries with high rates of tuberculosis. It protects children and babies from developing severe forms of tuberculosis, like meningitis or miliary TB. It is not used routinely in the United States. Your skin test may be positive because of BCG vaccination.

However, a positive skin test is most likely due to infection with TB bacteria if:

  • You recently spent time with a person who has active TB disease
  • You are from an area of the world where active TB is very common (Africa, Latin America, Asia, Eastern Europe and Russia)
  • You spend time where TB disease is common (homeless shelters, migrant farm camps, drug treatment centers, health care clinics. jails or prisons)
  • You were vaccinated more than 5-10 years ago
  • Your skin test is greater than 20 mm

Consider a blood test. Blood tests are not affected due to BCG - they will not give a false positive result due to BCG.

What is the difference between latent TB infection and TB disease?

A Person with Latent TB Infection (LTBI):

  • Usually has a skin test or a blood test result indicating TB infection*
  • Usually has a normal chest x-ray
  • Has TB bacteria in their body that are alive but inactive
  • Has no symptoms
  • Does not feel sick
  • Cannot spread TB to others
  • Can take treatment for LTBI to reduce their risk of developing TB disease

A Person with Active TB Disease:

  • Usually has a skin test or a blood test result indicating TB infection*
  • Usually has an abnormal chest x-ray
  • Has TB bacteria in their body that are active (growing)
  • Usually feels sick and experiences symptoms
  • May spread TB to others
  • Needs treatment to cure the active TB disease

* - A positive tuberculin skin test (TST) or a positive blood test only shows that you have been infected with the TB bacteria. Neither test can tell if you have TB disease, only if the TB bacteria are in your body.

How is latent TB infection treated?

Treating latent TB infection is essential to controlling and eliminating TB in the United States, because it substantially reduces the risk that the infection will progress to TB disease.

A person with TB infection can take medication called Isoniazid or Rifampin. This will kill the TB bacteria and greatly reduce the risk of TB disease from developing. Your doctor will decide which medicine is best for you. It is important to have health monitoring every month while taking either of these medications to be sure that you are not developing any harmful side effects. Your health care provider may order blood tests during your treatment.

There is now a 12 dose regimen that makes treating latent TB infection easier.

Considered one of the biggest breakthroughs in treatment for latent TB infection (LTBI) since the 1960s, the 12-dose regimen reduces treatment from 270 daily doses over 9 months, to 12 once-weekly doses over 3 months. It is a combination regimen of isoniazid and rifapentine; two of the most effective medications available for TB treatment.

Following the results of a recent large randomized control trial, the Centers for Disease Control and Prevention (CDC) released recommendations on the use of the new treatment regimen for LTBI:

  • It is recommended for otherwise healthy people aged 12 and older who are at an increased risk of developing TB disease
  • Close patient monitoring and the utilization of Direct Observed Therapy (DOT) in which a health care worker observes a person taking the treatment and monitors side effects is required for each of the 12 doses
  • It is an additional treatment option for LTBI and is not meant to replace other available treatment regimens

More information: CDC guidelines, Recommendations for Use of an Isoniazid-Rifapentine Regimen with Direct Observation to Treat Latent Mycobacterium tuberculosis Infection (MMWR 2011; 60: 1650-1653).

How is TB disease treated?

It takes a long time to kill all the TB bacteria. A person with TB disease typically must take 4 different medicines for 2 months:

  • Isoniazid
  • Rifampin
  • Pyrazinamide
  • Ethambutol

Then take Isoniazid and Rifampin for another 4-7 months depending on how much damage the bacteria have caused.

This treatment has been successful in treating TB disease for many years. In recent years, some TB bacteria strains have become resistant, (the medicines no longer kill the TB bacteria) to one or more of these drugs.

Multi-drug resistant (MDR) TB is resistant to the two strongest TB medicines, Rifampin and Isoniazid. The most common cause of drug resistance occurs when TB medications are not taken long enough and/or in the right amounts. Drug resistant TB is much more difficult and expensive to successfully treat. Extremely drug resistant (XDR) TB is a less common form of multi-drug resistant TB. There is resistance to Isoniazid and Rifampin, as well as most of the alternative drugs used against MDR TB. The Center for Disease Control and Prevention urges all health care practitioners to use directly observed therapy (DOT) in the treatment of tuberculosis.

How is TB spread?

When a person with active TB disease coughs or sneezes tiny droplets that contain TB bacteria are released into the air. If another person breathes air containing these droplets, they may become infected with the TB bacteria. However, not everyone infected with TB bacteria becomes sick. As a result, two TB-related conditions exist: Latent TB infection (LTBI) and Active TB disease - both of which are treatable and curable.

My TB test is positive, now what?

You will need to have a chest x-ray. If your chest x-ray is normal, this means you have been infected with the TB bacteria but your immune system has "walled off" the bacteria and is protecting you from getting sick. Your doctor may recommend that you take medication to kill the bacteria so you will lower your risk of ever developing active TB disease. If your chest x-ray is abnormal and/or you have symptoms of TB disease your doctor will order additional tests to see if you have active disease.

What are the symptoms of TB disease?

Symptoms of TB disease can include any or all of the following:

  • A cough lasting longer than 3 weeks
  • Trouble breathing
  • Pain in the chest
  • Feeling tired all of the time
  • Fever
  • Weight loss
  • Poor appetite
  • Night sweats
  • Swollen lymph nodes
  • Coughing up blood

See your doctor if you have these symptoms.

What is directly observed therapy (DOT)?

To increase the success of TB disease treatment and decrease the risk of drug resistance, a health care worker observes each dose of TB medication taken.

Most persons believe they are able to take their medication without help. But 6 - 9 months is a long time to take antibiotics, especially after you start to feel better. Health care workers who provide DOT offer encouragement to complete treatment. People are human and humans are sometimes forgetful. DOT health care providers help people remember to take their medicine. They also check for harmful side effects and make sure the medicines are working as expected.

What is TB?

Tuberculosis (TB) is caused by a bacteria called Mycobacterium Tuberculosis (M. tuberculosis). TB usually attack the lungs. Sometimes TB bacteria attack other parts of the body such as, the kidney, spine or brain. TB disease is a serious illness, but with proper treatment it can be cured.

Where can I learn more about TB?

The Northern Nevada Public Health's Tuberculosis Prevention and Control Program staff welcomes questions about tuberculosis. They can be reached at 775-785-4785.

There are many informative websites available:

Who is most likely to get TB?

Some people are more likely to be infected with the latent form of TB. These include:

  • persons who were born in a foreign country with high rates of TB
  • persons who have lived in a foreign country with high rates of TB
  • persons who have spent time with someone with active TB disease
  • persons who live or spend a lot of time in crowded places

Some people who are infected with latent TB have a greater risk of progressing to active TB disease. These include:

  • persons who became infected with TB in the last 2 years
  • children under 5 years of age
  • new immigrants from countries with high rates of TB - persons who have been in the United States for less than 5 years
  • persons with weakened immune systems
  • persons with certain kinds of lung disease, such as silicosis
  • persons with diabetes
  • persons who have had stomach or bowel surgery
  • persons who take certain medications for arthritis
  • persons who take prednisone or other steroids for extended periods of time
  • persons who have had cancer of the head, neck or leukemia
  • persons with end stage renal disease
  • persons who are extremely underweight (10% or more below ideal body weight)
  • persons with an abnormal chest x-ray suggestive of old healed TB disease
  • persons who had TB disease in the past but did not receive adequate treatment
  • persons with HIV infection. Persons with HIV infection have the greatest risk of progressing to active TB disease.

Last modified on 08/14/2023